One protester from the Rail and Maritime Transport union (RMT) had to be removed by security after he unfurled a banner and began berating the Mayor over planned transport cuts.

Boris Johnson had been answering a question about claims made by the RMT that two trains on the Northern line came close to a head-on collision last week.

As he tried to explain that there appeared to have been “no risk to staff or customers”, RMT assistant general secretary Steve Hedley stood up and interrupted.

Assembly chair Darren Johnson immediately halted the meeting but Mr Hedley continued to list his grievances, including the planned closure of Whitechapel Underground station’s ticket office and the removal of guards from Overground trains, which will see more than 100 TfL staff lose their jobs.

The Mayor and London Assembly Members sat impassive, ignoring the heckling as Mr Hedley was removed from the chamber. More than a dozen other anti-transport cuts activists left with him.

Last month, protesters from the Fire Brigades Union forced the temporary adjournment of Mayor’s Question Time when they conducted a similar demonstration.

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